Underwater transducer



March 7, 1961 N. N. ESTES UNDERWATER TRANSDUCER 2 Sheets-Sheet 1 FiledOct. 6, 1949 3mm/vbo@ V. NESTES March 7, 1961 N. N. ESTES UNDERWATERTRANSDUCER 2 Sheets-Sheet 2 Filed 061i.I 6. 1949 3mm NN ESTES UnitedStates Patent O UNDERWATER TRANSDUCER Nelson N. Estes, 319 PinewoodAve., Silver Spring, Md.

Filed Oct. 6, 1949, Ser. No. 119,981

4 Claims. (Cl. 116-137) (Granted under Title 35, U.S. Code (1952), sec.266) This invention relates generally to sound generating apparatus andmore particularly to a device of this character adapted for producingwithin a body of water acoustic signals of widely varying amplitudes andfrequencies for actuating thereby acoustically sensitive mines or thelike submerged therein.

Heretofore considerable diiculty has been encountered in sweeping minesof the acoustically sensitive type that are adapted to detonateresponsively to the reception thereof of acoustical signals receivedthereby from the propellers of a passing ship. The principal diculty insweeping mines of this character is that the controls therefor aregenerally set to respond only to such sound frequencies as are producedby the larger type vessels and thereby discriminating selectivelytherebetween and smaller surface vessels which may pass above such minesunharmed.

A further distinguishing characteristic of such mines is that theircontrols are frequently so designed as to respond only to selected ratesof .approach to peak amplitude of the sound energy received thereby andwhich, while making such mines considerably more dicult to sweep, wereprimarily intended for delaying detonation of the mine until such timeas the target vessel has moved within the effective range thereof.

To successfully sweep mines of the type indicated, it is necessary toduplicate artifically, within the water surrounding the mine, anacoustic signal similar in substantially every respect to that producedby a passing vessel. Of the various devices heretofore devised andemployed to accomplish this, the most common form thereof is known asunderwater speakers adapted magnetically to vibrate a diaphragm wherebyacoustic signals are transmitted therefrom throughout the surroundingwater. Such devices, though effective for short ranges, are highlyvulnerable to sudden pressure increases as may be caused by theexplosion of a mine in the proximity thereof and therefore, by reason oftheir initial cost and operation expense, are generally not consideredpractical for mine sweeping application. Other such devices includingunderwatersirens and the like generally lack the frequency responserequired for effectively sweeping mines of widely varyingcharacteristics.

The device of the present invention possesses advantages over the priorart for the purposes disclosed not only in its simplicity of design butfurther by reason of its effectiveness of operation wherein ahomogeneous mixture of steam and air is caused to be expelled at acontrolled velocity through a vibratory nozzle portion Athereof wherebya continuous signal of predetermined frequency and high energy output isproduced and caused to be radiated therefrom through the surroundingVwater for actuation thereby of acoustically responsive rice A furtherobject of the present invention is to provide an underwater transducerof high energy output capable of projecting throughout a predeterminedsubmerged area an acoustical signal of a selectable frequency range.

A still further object is to provide a new and improved underwatertransducer wherein the steam and air required for the operation thereofmay be homogeneously mixed in proportions selectable for producingtherein the operational characteristics desired.

A still further object is to provide an underwater transducer which isrigid in construction, inexpensive to manufacture yet highly efficientand accurate in its operation.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a view in section of the transducer according to a preferredembodiment thereof;

Pig. 2 is an enlarged sectional view through the vibratory nozzleassembly;

Fig. 3 is a sectional view of the vibratory nozzle taken along the line3--3 of Fig. l, somewhat reduced and partly broken awa'y; and

Fig. 4 is a view in elevation showing the application of the deviceaccording to the arrangement thereof illustrated in Fig. l, as suspendedfrom a vessel for movement thereof through the mine fields.

Referring now to the drawings and more particularly to Fig. 1 thereof,the transducer generally designated 5 is shown as comprising acylindrical body portion 6 formed preferably from stainless steel, orthe like, and including adjacent one end thereof a recess 7 wherein isthreaded a closing plug 8 therefor. The recess 7 terminates into athickened body portion at 9 whereby sulficient weight is providedthereby for maintaining stability of the transducer within the waterduring the operation thereof. Rising centrally from the base of therecess 7 and preferably formed as an integral part of the body is astand pipe 10 the free end thereof being internally machined into aconically formed concave seat at 11 for receiving therein acorrespondingly shaped nozzle end 12 of a flow adjustment screw 13threaded with the cap piece at 14 and movable into or out of the seat 11by rotation within the threads of the cap as a wrench or like tool isapplied to the hex head portion 15 theroef.

Provided about the shank of the screw 13 is an annular groove 16disposed in uid communication with an air supply tube 17 throughintersecting bores 18 and 19. Arranged for being received into athreaded mouth portion 20 of the bore 19 is a pipe section 21 onto whichis sleeved the tube 17, the tube being thereafter secured to the pipesection as by clamp rings 23. v

The width of groove 16 permits considerable adjustv ment of the s'etscrew 13 within the cap before fluid communication between the grooveand bore i8 is interrupted. A bore 25 centrally disposed within setscrew 13 and intersecting a transverse bore 26 in the latter iseffective to communicate air from the groove 16 to the mouth of thenozzle end 12 of the screw, the air thereby being jetted into the boreof the stand pipe at a velocity controllable from the surface of thewater by any suitable valve arrangement connected conventionally in theair supply. j

A bore 27 provided in the cap and arranged opposite the bore 19 issuitably threaded at 28 for receiving therein the threaded end sectionof a pipe member 29 adapted for communicating steam from a supplyconduit 30, con- 0 nected therewith as by clamps 31, to the chamber 7,

the steam so admitted to the chamber thereafter being forced through theconically formed gap 33 and into the agrarias air stream from bore 25thereby to mix therewith before being expelled from the ytransducer frombetween the lips of a vibratory nozzle assembly generally designated 35.

Adjustment of the gap 33, thereby to vary selectively the proportions ofsteam and air in the mixture, is accomplished by rotation of the screw13 in a manner heretofore set forth either into or out of the mouth ofthe stand pipe l0, the screw thereafter being secured in an adjustedposition by the tightening of the lock nut 36 thereon.

The nozzle assembly 35 is comprised of a tubular section 37 suitablythreaded at 38 for being received into the threaded end portion of thebore 39 formed as a continuation of the bore of the stand pipe lil. Theother end of the tube 37 is flattened at 40 for being received between apair of exible vibrating elements 41 formed from any resilient materialsuch, for example, 'as rubber and adapted for being secured along theiredges, as shown, by plates 42 drawn into clamping engagement therewithas by rivets 43.

A suitable vulcanizing material applied to the outer surface of thetubular section 37 and the inner surface of the flexible element 41provides an effective seal therebetween as at 44, Fig. 3, as the edgeportions of the elements are drawn tightly over the tube and clampedbetween the plates 42 at the ytime of the nozzle assembly.

A bracket member 46, arranged over the pipe section 37, Figs. l and 2,and preferably furnace brazed thereto at 47, includes a pair ofoutwardly extending bifurcated arm sections 48 adapted for receivingbetween the'bifurcated portions 49 thereof the edge portions of theplates 4,2, Fig. 3. A plurality of bolts 50, arranged as illustrated,are effective when tightened to draw the forks 49 of the bracket to theplates and thus provide a rigid supporting structure for the nozzle froma position adjacent the transducer housing. Y

A ring member 52 secured to the head portion 15 of the adjustment screwat 54 is adapted for receiving `therein a cable ring 55 by which thetransducer is suspended within the water from a supporting cable 56therefor preferably arranged for depending from the bow end portion ofthe sweeping vessel 57 substantially as illustrated in Fig. 4.

Air and steam supplied respectively from the ships compressors andboilers when properly mixed within the transducer housing and dischargedtherefrom through the vibratory nozzle portion 35 thereof is effectiveto produce, for transmission throughout the surrounding water, anacoustic signal of great amplitude and of widely varying frequencycharacteristics controllable at will 'from the surface vessel by theregulation of the volume of the air and steam supplied therefrom.Acoustic signals of the character indicated when projected through thewater before a moving vessel are generally effective to detonate eachacoustically controlled mine 60 lying in the path of the vessel far inadvance 'of lthe passing of ,the vessel thereover.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. it is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as speciiically described.

The invention described herein may be' manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent ofthe Uni-ted States is:

1. A transducer of the character disclosed for underwater soundtransmission comprising, a housing, means including a discharge port insaid housing for communieating steam from a source under pressurethrough said housing, means for introducing `air under pressure `intosaid steam communicating means for mixing the air homogeneously thereinwith said steam before the discharge thereof through said port, and aflat vibratory acoustic nozzle of generally triangular configuration andhaving Ithe interior thereof connected to said housing in fluid circuitwith said port, said nozzle including a pair of resilient vibratoryelements edge clamped along two sides thereof for exhausting saidmixture therebetween through a normally closed outlet provided at thethird side thereof, thereby to vibrate the elements responsively theretowhereby a low frequency acoustic signal is transmitted through theVsurrounding water.

2. A transducer of the character disclosed for underwater soundtransmission which comprises, a housing, means forming a passagewayincluding a discharge port in said housing for communicating steam froma source under pressure through said housing, a mixing valve arranged insaid passageway for controlling the flow of steam therethrough, meansforming a part of said valve for admitting air from a source underpressure to said passageway for mixing the air therein with 'said steambefore discharge of the latter through said port, and a flatvibratorynozzle of generally triangular configuration on said housing influid circuit with said discharge port and including a pair of edgeclamped resilient plate members secured in face adjacency with respectto each other and adapted to exhaust therebetween the steam and airmixture from said housing thereby to cause the plate members to vibrateat selectable frequencies correlative to the air and steam ratio of theexhausting mixture passing therethrough whereby low frequency acousticsignals are transmitted through the surrounding water.

3. A transducer of the character disclosed for underwater soundtransmission comprising, a cylindrically formed housing adapted Vforsubmergence within a body of water and having therein a centrallydisposed recess, a standpipe having a conically concaved end portionpro` jecting centrally upward from the base of said recess, an annularcap member disposed to close said recess thereby forming in said housingabout said standpipe an annular chamber, port means in said cap foradmitting steam from a source under pressure to said chamber for passingtherefrom into the opening of said standpipe, an adjustment screwmovable within said cap and having a conically formed end portion forbeing received into the concaved portion of said pipe for adjustablyregulating the passage of steam thereinto, means forming a centrallydisposed bore in said adjustment screw and terminating in a nozzleadjacent the apex of said conically formed portion thereof, meansforming a port in said cap for admitting air from a source underpressure to said nozzle whereby the air is jetted therefrom into theopening of said pipe for mixing homogeneously with the steam in saidpipe opening, means kforming a continuation of said pipeopening'terminating in `a discharge port and disposed for exhaustingfrom said housing said homogeneous mixture, a flat vibratory acousticnozzle of generally triangular configuration secured to the housing andarranged in fluid communication with said discharge port, saidl acousticnozzle Vincluding a pair of resilient vibratory elements edge clamped attwo sides thereof and disposed in face adjacency for receivingtherebetween the mixture from said discharge port whereby an ocousticsignal is transmitted throughout the surrounding water as said elementsare vibrated in response to the discharge of said mixture between thenormally closed outlet provided at the third side of said acousticnozzle. K

4. A transducer of the character disclosed adapted Yfor underwater soundtransmission which comprises, a cylindrically formed housing forsubmergence within a body of water and having a centrally disposedrecess therein, a standpipe having a conically concave end portion extending upwardly from the base of said recess,Y an annular cap memberarranged for closing said recess thereby forming in said housing aboutsaid standpipe an Vannular chamber, y rnezms forming a port in said capfor admitting steam from a source under pressure to said chamber forpassage therefrom to the opening of said standpipe, a screw havingthereon a conically formed end section disposed to provide foradjustment of the opening of said standpipe for controlling selectivelythe passage of steam thereto, means forming a centrally disposed bore insaid screw and originating at the apex of said conically formed endportion thereof to form a nozzle adapted for projecting within theconcave por tion of said standpipe, means forming a port in said cap foradmitting air from a source under pressure to said nozzle for jettingtherefrom into the opening of said pipe for mixing homogeneously thereinwith said steam, means forming a discharge port in fluid circuit withsaid pipe opening and adapted for discharging from said housing saidsteam and air mixture, a triangularly congured vibratory acoustic nozzleassembly on said housing in fluid circuit with said discharge port andincluding a pair of edge clamped resilient vibrator elements, a tubularpipe section secured within said discharge port and including aiiattened portion disposed to extend between the surfaces of saidelements, means including a pair of opposingly arranged plates forclamping said elements in face adjacency to the surface of the attenedportion of said pipe section whereby the steam and air mixturedischarged therethrough is expelled into the water from between thenormally abutting surfaces of said elements to produce an acousticsignal for transmission through the surrounding water.

References Cited in the le of this patent UNITED STATES PATENTS 343,938Williams June 15, 1886 852,646 Blake May 7, 1907 1,113,400 BaumgartnerOct. 13, 1914 1,169,090 Lucke Ian. 18, 1916 1,680,757 Yablick Aug. 14,1928 1,927,054 Williams Sept. 19, 1933 2,350,187 Pfeiffer May 30, 1944

